The use of iodine containing disinfectants containing potassium or sodium iodide and elemental iodine in an aqueous phase for medicinal purposes is well known in the art (e.g. tincture of iodine). In addition to the above ingredients, such disinfectants sometimes contain calcium iodide as well as varying amounts of solubilizing intermediates such as ethanol, isopropanol, or glycerine.
During the past few years, iodine products containing surface active anionic, cationic, and preferably, nonionic substances have been introduced to the marketplace under the general designation of iodophors. These products are used not only in medicine, but also in the food industry. This group of iodophors contains, in addition to the above mentioned surface active substances and elemental iodine and iodides, varying amounts of phosphoric acid.
Additionally, the surface active substances are sometimes replaced partially or completely by high polymer substances such as for instance polyacrylates or other substituted polycarboxylic acids. Such produces may also contain various amounts of solubilizing intermediaries such as isopropanol or ethanol.
It has been shown that the aqueous or alcohol containing solutions which are used as pharmaceutical products give unfavorable results when used for disinfecting solid surfaces which are to come into contact with foodstuffs after disinfection and rinsing. Additionally, some surfaces (e.g. composed of synthetic materials) have shown brownish discolorations after treatment. Also, the stability of the disinfecting solutions has been insufficient, which is noticable from lightening of the characteristic brownish-yellow color of the elemental iodine in the aqueous phase.
The group of iodophors, on the other hand, do exhibit good bacteriological activity when used to disinfect solid surfaces. However, certain disadvantages have become evident in their application. For instance, even when foam inhibitors are used, foam-free operation is not possible when the iodophors are used in equipment designed for processing various foodstuffs. Additionally, such preparations pollute waste water with their surface active as well as non-surface active polymeric compounds, e.g. by elevating the so-called COD values (chemical-oxygen demand). It has also been shown that the rinsability of iodophors is not as good as that of substances which are free of surface active agents. Additionally, stress corrosion caused by nonionic, ethoxylated and/or propoxylated block polymers, which serve as the iodine carriers, have been observed in acrylic glass used in milking machine pipes.
Another disadvantage of the iodophors is the fact that the dissolving intermediaries, such as for instance ethyl alcohol and isopropyl alcohol, not only pollute the waste water, but also require special safety precautions during manufacture (explosion-proof installations) and during packaging (degassing vents) due to their relatively low flash point. Examples of references disclosing prior art iodine-containing compositions of the type discussed above are given below:
West German Pat. No. DT 25 27 795 B2 discloses aqueous compositions containing from 0.5 to 3 percent by weight of iodine, from 10 to 30 percent by weight phosphoric acid, from 5 to 30 percent by weight of acetic acid, and from 0.5 to 20 percent by weight of a polymer having a molecular weight between 500 and 10,000 of the formula ##STR1## where X is 65-90% --COOH and 10-35% ##STR2## U.S. Pat. No. 3,220,951 to Cantor et al discloses detergent iodine compositions containing iodine, a water soluble ethoxylated nonionic surface active agent/detergent as a carrier for the iodine and an acid which is hydroxyacetic acid, either alone or in admixture with phosphoric acid. PA1 (a) from about 0.1 to about 3% by weight, preferably about 1 to about 2% by weight, of I.sub.2, PA1 (b) from about 0.2 to about 6% by weight, preferably about 2 to about 4% by weight of potassium iodide or sodium iodide (or a mixture thereof), and PA1 (c) from about 1 to about 15% by weight of orthophosphoric acid,